2,450 research outputs found
Strong law of large numbers for supercritical superprocesses under second moment condition
Suppose that is a supercritical superprocess on a locally
compact separable metric space . Suppose that the spatial motion of
is a Hunt process satisfying certain conditions and that the branching
mechanism is of the form where , and is a kernel from to
satisfying Put
. Let be the largest
eigenvalue of the generator of , and and be
the eigenfunctions of and (the dural of ) respectively
associated with . Under some conditions on the spatial motion and
the -transformed semigroup of , we prove that for a large class of
suitable functions , we have for any finite initial measure on with compact support, where
is the martingale limit defined by
. Moreover, the
exceptional set in the above limit does not depend on the initial measure
and the function
A zero-dimensional combustion model with reduced kinetics for SI engine knock simulation
High load performance and fuel economy of gasoline engines are limited by knocks. Such limitations
are becoming worse when the engine is heavily super-charged for high BMEP outputs. Spark ignition
timing retardation has been an efficient method to avoid the knock but results in reduced engine
performance and poor fuel economy. A better understanding of knock, which could be used to optimize
the engine design, ignition timing optimization in particular, is important. In this research, a simulation
model for SI engine knock has been developed. The model is based on a three-zone approach
(unburned, burning and burned zones). The Tanaka’s reduced chemical kinetic model for a commercial
gasoline fuel with an RON of 95 has been modified and applied in both burned and unburned zones
incorporated with the LUCKS (Loughborough University Chemical Kinetics Simulation) code. Both
post-flame heat release and pre-flame autoignition have be simulated. The burning zone uses equilibrium
combustion thermodynamic models. The simulated results have been validated against experimental
results, and good agreements have been achieved
Incorporating Ultrasound Tongue Images for Audio-Visual Speech Enhancement through Knowledge Distillation
Audio-visual speech enhancement (AV-SE) aims to enhance degraded speech along
with extra visual information such as lip videos, and has been shown to be more
effective than audio-only speech enhancement. This paper proposes further
incorporating ultrasound tongue images to improve lip-based AV-SE systems'
performance. Knowledge distillation is employed at the training stage to
address the challenge of acquiring ultrasound tongue images during inference,
enabling an audio-lip speech enhancement student model to learn from a
pre-trained audio-lip-tongue speech enhancement teacher model. Experimental
results demonstrate significant improvements in the quality and intelligibility
of the speech enhanced by the proposed method compared to the traditional
audio-lip speech enhancement baselines. Further analysis using phone error
rates (PER) of automatic speech recognition (ASR) shows that palatal and velar
consonants benefit most from the introduction of ultrasound tongue images.Comment: To be published in InterSpeech 202
Incorporating Ultrasound Tongue Images for Audio-Visual Speech Enhancement
Audio-visual speech enhancement (AV-SE) aims to enhance degraded speech along
with extra visual information such as lip videos, and has been shown to be more
effective than audio-only speech enhancement. This paper proposes the
incorporation of ultrasound tongue images to improve the performance of
lip-based AV-SE systems further. To address the challenge of acquiring
ultrasound tongue images during inference, we first propose to employ knowledge
distillation during training to investigate the feasibility of leveraging
tongue-related information without directly inputting ultrasound tongue images.
Specifically, we guide an audio-lip speech enhancement student model to learn
from a pre-trained audio-lip-tongue speech enhancement teacher model, thus
transferring tongue-related knowledge. To better model the alignment between
the lip and tongue modalities, we further propose the introduction of a
lip-tongue key-value memory network into the AV-SE model. This network enables
the retrieval of tongue features based on readily available lip features,
thereby assisting the subsequent speech enhancement task. Experimental results
demonstrate that both methods significantly improve the quality and
intelligibility of the enhanced speech compared to traditional lip-based AV-SE
baselines. Moreover, both proposed methods exhibit strong generalization
performance on unseen speakers and in the presence of unseen noises.
Furthermore, phone error rate (PER) analysis of automatic speech recognition
(ASR) reveals that while all phonemes benefit from introducing ultrasound
tongue images, palatal and velar consonants benefit most.Comment: Submmited to IEEE/ACM Transactions on Audio, Speech and Language
Processing. arXiv admin note: text overlap with arXiv:2305.1493
Atomic spatial coherence with spontaneous emission in a strong coupling cavity
The role of spontaneous emission in the interaction between a two-level atom
and a pumped micro-cavity in the strong coupling regime is discussed in this
paper. Especially, using a quantum Monte-Carlo simulation, we investigate
atomic spatial coherence. It is found that atomic spontaneous emission destroys
the coherence between neighboring lattice sites, while the cavity decay does
not. Furthermore, our computation of the spatial coherence function shows that
the in-site locality is little affected by the cavity decay, but greatly
depends on the cavity pump amplitude.Comment: 4 pages, 5 figures, accepted by PR
Efficient dealkalization of red mud and recovery of valuable metals by a sulfur-oxidizing bacterium
Red mud (RM) is a highly alkaline polymetallic waste generated via the Bayer process during alumina production. It contains metals that are critical for a sustainable development of modern society. Due to a shortage of global resources of many metals, efficient large-scale processing of RM has been receiving increasing attention from both researchers and industry. This study investigated the solubilization of metals from RM, together with RM dealkalization, via sulfur (S(0)) oxidation catalyzed by the moderately thermophilic bacterium Sulfobacillus thermosulfidooxidans. Optimization of the bioleaching process was conducted in shake flasks and 5-L bioreactors, with varying S(0):RM mass ratios and aeration rates. The ICP analysis was used to monitor the concentrations of dissolved elements from RM, and solid residues were analyzed for surface morphology, phase composition, and Na distribution using the SEM, XRD, and STXM techniques, respectively. The results show that highest metal recoveries (89% of Al, 84% of Ce, and 91% of Y) were achieved with the S(0):RM mass ratio of 2:1 and aeration rate of 1 L/min. Additionally, effective dealkalization of RM was achieved under the above conditions, based on the high rates (>95%) of Na, K, and Ca dissolution. This study proves the feasibility of using bacterially catalyzed S(0) oxidation to simultaneously dealkalize RM and efficiently extract valuable metals from the amassing industrial waste
Clinical observation on fibrin glue technique in pterygium surgery performed with limbal autograft transplantation
AIM: To compare the efficiency and safety of fibrin glue to suture technique in pterygium surgery performed with limbal autograft.<p>METHODS: A prospective randomized clinical trial was carried out in 60 eyes of 48 patients operated for primary nasal pterygium. Autologous limbal graft taken from the superotemporal limbus was used to cover the sclera after pterygium excision under local anesthesia with 2% lidocaine. In 22 cases(30 eyes), the transplant was attached to the sclera with a fibrin tissue adhesive(group 1)and in 26 cases(30 eyes)with 10-0 Virgin silk sutures(group 2). Patients were followed up at least for 3 months. Time of operation, matching degree of graft and visual analogue scale(VAS)score were mainly observed and recorded. <p>RESULTS: Patient symptoms were significantly less and biomicroscopic findings were better in group 1. Pterygium recurrence was seen in 1 case of group 1, and 1 case of group 2. Average surgery time was shorter(<i>P</i><0.01)in fibrin group. <p>CONCLUSION: Using fibrin glue for graft fixation in pterygium surgery causes significantly less postoperative pain and shortens surgery time significantly
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